1. Field of Invention
The present invention relates to transflective electro-optical devices which can interchangeably perform reflective display by using external light and transmissive display via light-source light. The invention also relates to an electronic apparatus provided with such a device.
2. Description of Related Art
In a transflective electro-optical device, such as a transflective liquid crystal display device, reflective display is performed in a bright place by using external light while a light source is turned off. In a dark place, transmissive display is performed by using light emitted from the light source that is turned on. In particular, reflective display is performed by having incident external light reflected off of areas of a transflective film other than slits provided therein, which are used for light transmission, to the exterior of the device via an electro-optical material layer formed of liquid crystals or the like. On the other hand, transmissive display is performed by transmitting light emitted from a light source provided at a back side of a transflective film, and by emitting this transmitted light to the exterior of the device via the electro-optical material layer formed of liquid crystals or the like. This type of transflective electro-optical device has been widely used as a display device of a portable electronic apparatus, such as a mobile phone, since there is a strong demand for electrical power conservation, and in addition, this type of device may be optionally used in a dark place.
In addition, a color reflective electro-optical device, which performs color display by using color filters (hereinafter “selective-transmission color filter”) formed of resin materials colored by dyes or pigments, has also been developed. However, this type of color filter has been formed so that each pixel selectively transmits light in a predetermined wavelength range and selectively absorbs light outside of that range, and hence, the optical efficiency for this type of color reflective electro-optical device is basically low. Accordingly, when color reflective display is performed by this type of selective-transmission color filter using external light that only has a limited light intensity, the brightness of the display is generally decreased. Accordingly, in order to create a bright color reflective display, a method in which light in a predetermined wavelength range is not selectively transmitted but is selectively reflected has also been developed. For example, in Japanese Unexamined Patent Application Publication Nos. 8-304626, 9-146088, and 2000-231097, cholesteric liquid crystal and a color filter (hereinafter “selective-reflection color filter”) which selectively reflects light in a predetermined wavelength range by using a polymer film or the like have been disclosed. According to the techniques disclosed in these publications, by increasing the optical efficiency of external light, a bright, color reflective display can be created.
When the selective-reflection color filter described above is applied to the transflective electro-optical devices, a bright reflective display can be created. However, when transmissive display is performed, light-source light which is selectively transmitted through the selective-reflection color filter, that is, light with a color complementary with respect to the color of light that is selectively reflected, is transmitted through the selective-reflection color filter as light-source light, and then the light is emitted to the exterior of the device. That is, when transmissive display is performed, a display in colors, that are complementary to those of a reflective display, is created. Accordingly, when a display device is formed so that the color tones are normally displayed in color reflective display, a problem may arise in that the color tones are abnormally displayed in color transmissive display.
As a result, according to any of the techniques described above, there has been a problem, which is difficult to address or solve, in that a color display having normal color tones and a bright, color reflective display cannot be compatible with each other in a transflective electro-optical device.